System of contboii



UNITED STATES PATENT OFFICE.

BUDOLP E. HELLMUND, OF PITTSBURGH, PENNSYLVANIA, ABBIGNOB TO WEST- INGHOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION 0P PENNSYLVANIA.

SYSTEM OF CONTROL.

Specification of Letters Intent.

Patented Sept. 16, 1919.

Application filed May 8, 1918. Serial No. 96,234.

To all whom it may concern:

Be it known that I, RUDOLF E. HELLMUND, a subject of the Emperor of Germany, and a resident of Pittsbur h in the county of Allegheny and State 0% Pennsylvania, have invented a new and useful Improvement in Systems of Control, of which the following is a specification.

.My invention relates to systems of control and especially to the regenerative control of direct-current electric railway motors and the like.

One of the objects of my invention is to provide a system of the above-indicated character which shall be relatively simple and inexpensive in construction and efi'ective and reliable in operation and which shall embody certain novel and advantageous operating features, as hereinafter more fully set forth.

In a'more specific aspect, it is an object of my invention to provide, in a regenerative control system a the class under consideration, means for inhcrentlv and automatically producing a negative compounding effect in the main momentum -driven machines, whereby an incipient increase of regenerated current is immediately counteracted b a corresponding decrease of main field-wmding current, and, in addition, an auxiliary exciting generator for the main field windings which shall have a positive compound ing characteristic and thus serve to aid the inherent regulating action just recited.

By the term negative compounding characteristic is meant an inherent tendency to decrease the main-field-winding current upon an incipient increase of mainarmature current, and vice versa; while the expression positive compounding characteristic signifies that the field-winding and armature currents inherently tend to concurrently vary in the same direction, that is, the one increases when the other increases.

My invention may best be understood by reference to the accompanying drawing wherein Figure 1 is a diagrammatic view of a system of control embodying my invention; Fig. 2 is a similar view. of a modification thereof; and Fig. 2A is a chart serving to set forth certain flux relations in the machine that is shown in Fig. 2.

Referring to the drawing, the system here shown comprises a plurality of supply-circuit conductors respectively marked Trolley and Grounda plurality of main dynamo-electric mac ines res ectively having armatures A1 and A2 and field-magnet windings F1 and F2 of the series type; a plurality of main-circuit regulating resistors R1 and R2 that are associated with the respective main machines in a manner to be described; and an auxiliary motor-generator set or dynamotor that is adapted to be driven from the supply circuit and to excite the main field windings, as set forth more fully later.

The auxiliary motor generator set is shown as comprising a driving armature M and an exciting armature G that may be mechanically associated with the armature M in any suitable manner, as by a shaft 8; a plurality of field-magnet windings MF and GB of the series type for the respective armatures M and G; and a shunt or supplyeircuit-excited] field-magnet winding GFl for the armature G.

An auxiliary variable resistor ARI is connected in series relation with the supplycircuit-exc'ited field-magnet winding GF1 and is adapted to be varied in active circuit value by a plurality of switches 1 and 2; and a second auxiliary resistor A32 is adapted to be connected in shunt relation to the series field winding GF by the closure of switch 3, and the value of the resistor may be varied by the manipulation of switches 4 and 5.

Inasmuch as my present invention pertains only indirectly to the type of re enerative control system that is employe I have not deemed it necessary to show and describe means for initially connecting the various machines as illustrated, or means for inaugurating regenerative operation. The main system, here shown for illustrative purposes only, isvfull set forth and claimed in my co-pending application, Serial No. 44,443, filed August 9, 1915.

Assuming that regenerative operation has been started in any suitable manner and that the various circuit connections are as illustrated in the drawing, such connections may be traced as follows: one main circuit is established from the trolley through junclZlOIlrPOlIllI 10, conductor 11, main armature A1, conductor 12, junction-point 13, maincircuit resistor R1, switching device 14, which is here conventionally shown as an arrow-head, unction-point 15. and conductors 16 and 17 to the negative conductor Ground. A second similar main circuit is established from the junction-point 10 through conductors 18 and 19, main armature A2, conductor 20, junction-point 21, main-circuit resistors R2, switching device 22, which corresponds to the switching device 14, and thence through junction-point 15 as just recited.

One terminal 23 of the auxiliary exciting generator G is connected through'conductors 24 and 25 to thc 'conductor 16 and junctionint '15,"where the circuit divides, one b anch includin switching device 14, maincircuit resistor 1, 'unction-point 13, main field windin F1 an conductor 26 to a junc-r tion-point 2 and the other branch including switching device 22, main-circuit resistor R2, junction-point 21, main field winding F2 and function-point 27, whence circult is comp eted through conductor 28 to the other terminal 29 of the auxiliary exciting armature G.

An auxiliary circuit is completed from the conductor 18 through conductors 30 and 31,'the driving armature windin M of the motor-generator set, series field winding MF, conductor 32, series field windin GF and conductor 25 to the negative con uctor 17. The load current of the motor-generator set thus traverses both of the series field windings MF and GB, for purposes to be described.

A furtherau'xiliary circuit is com leted from the conductor 30 throu h con actor 33, auxiliar resistor ARI, eld winding GFI, and t ence through conductor 24 as previously described. Thus the field wind mg GFI is connected, through the variable resistor ARI, across the supply circuit.

As indicated by the positive and negative signs and by the legend Diflcrential, the series field windin GF is ada ted to increase the deliver voltage of t e exciting armature G upon increased load conditions of the motor-generator set, whereas the sup ply-circuit-excited field winding GFl exerts a ne tive or opposing action, or, in other wor s, is difi'erentially related with respect to the series field winding GF, which, under normal conditions, predominates over the shunt field winding GFI. Such relation of parts causes the exciting armature G to have a positive self-compounding characteristic, that is to say, the eifective flux delivered to the armature winding G is such that the voltage roduced thereby varies in accordance wit load conditions of the motor-generator set. This action is of advantage in aiding the negatlve compound characteristic of the main motors during the re enerative eriod, as set forth later.

t should e noted that, inasmuch as the driving armature M is rovided with straight series excitation, e armature is but slightl Y liable to flash-over troubles for the well-known reason that, in case of an interruption of supply-circuit voltage and a sudden resumption thereof such as occurs, for exam le, when the current-collecting member of the vehicle leaves the wire temporaril the field flux of the driving motor of t e motor-generator set is'built up in a relatively ra 1d manner. Thus, the field flux is not no uly distorted by the initial restored armature-current fiux and, consequently, flash-over conditions do not obtain.

Moreover, by reason of the differential relation of the field windings GF and GFI of the excitin armature G, the sudden rise of regenerate voltage which tends to occur upon an interruption of supply-circuit voltage, and which rise if unchecked, would tend to produce abnormally high voltage between commutator bars of the various machines and probably flash-over troubles as a result, is prevented from reaching an un desirably high value by reason of the fact that any increase of the flux produced by the series field winding GF is counteracted or annulled by a correspondingly increased negative'or diii'erential action of the field winding GFl. The field windings may be so designed that, under the circumstances just mentioned, the counteractin effect of the supply circuit excited fie d magnet winding GF1 will overcome the positive energizln action of the series field winding GF and t us cause a reduction of the main field'windin excitation, whereby the abovementioned angerous rise of voltage is effectively precluded.

Furthermore, the motor-generator set un der consideration lends itself particularly well toward producing a damping efiect upon voltage fluctuations of the supply circuit. Such damping eflect' is, in part,- provided b the well-known choke-coil action of the s unt field winding GFl which, as is customary, comprises a relatively lar e number of turns of fine wire, and partial y by the buffer or dam-ping action of the auxiliary resistor AR2 when connected in shunt relation to the series field winding GF. Still further damping effect may be obtained, if desired, by introducing dampers of the well-known gridiron type, for ex ample, in the polar-faces of the auxiliary exciting gcnerator. The damping effect in question is desirable in some instances, by reason of the fact that it is then possible for over-voltage relay devices to effect the opening of mam-circuitswitches, in accordance with customary practice, because of the time element involved, before the abovementioned rise of voltage exceeds a predetermined value for which the relays are set, thereby preventing injury to the variou dynamoelectric machines.

lot)

Assuming that regenerative operation has been inaugurated, the operation of the aboveture G, whereas the currents in the allied mam armatures and field windings A1 and F1, for example.1i travel in opposite direc tions. As a res t, an incipient increase'o'f regeneratedcu'rrent produces a correspondingly augmented voltage drop in the corresponding main-circuit resistor, whereby the exciting voltage available for delivery to the correspondin main field winding from the approximate y constant-voltage armature winding thus the regenerated current in the corresponding main armature is reduced to the normal and desirable substantially constant value. The reverse action, of course, occurs upon an incipient decreaseof regenerated current in either main armature. Such action is more fully set forth in my aboveidentified co-pending application but it is believed that the foregolng description will be suflicient for the purposes of the present specification. However, under the above-mentioned conditions, a further inherent regulating action takes place, since, when an increased current traverse a main-contact resistor, the general result corresponds to a virtual increase of circuit resistance, whereby a decreased current traverses the corresponding main field windin and the auxiliary excitingarmature G. lonsequently, the reduced energy demand from the armature G causes a corresponding decrease of the current traversing the drivingaarmature M and the series field windings F and GF, whereby the volta e of the auxiliary armature G 1s according y reduced by reasonvof the difierential action of the field windings GF and GFI, or, in other words, because of the positive comiounding characteristic of the ar-- mature It Wlll be understood that, under the converse condition of an incipient decrease of the regenerated current, the flux of the series field winding GF will be correspondingly augmented and thus induce an increased voltage in the auxiliary armature G. The action just described, of course takes place in a relatively rapid manner and the positive compounding eflect of the exciting generator thus tends to aid the inherent negative compounding efi'ect of the main machines to immediately and automatically counteract incipient changes of regenerated current and thus maintain a substantially constant flow of current to the supply circuit. a

As pointed out in detail, in my abovelclusive, to efiect a is accordingly decreased, and

armature windi' grojections. A series field winding mentioned co-pending application, the swltching devices 14 and 22 that are associated wlth the main-circuit resistors R1.

and R2 may be varied, preferably in an automatic manner in accordance with the value of regenerated current, as. the speed of the momentum-driven machines decreases. However, in the present system, further or sole regulation may be obtained by suitably manipulating the switches 1 to 5, in-

dual increase of the volta of the auxi ia'ry armature G as the vehic e speed decreases. The last-mentioned regulation involves the switching of relatively small currents, and the use of relatively small and 'inex ensive switches, as will be understood, and is advantageous in these respects.

'Reference may now be had to Fig. 2, wherein the main circuit connections are the same as those described in connection with Fig. 1. In the present system, the exciting relation with a old-magnet winding GF2, which .corresponds to the series field winding GF of Fig. 1, to* excite the main fieldwmding circuits in a. manner similar to that already se't'forth. The series field winding GF2 is provided with the shunting resistor A112 for the same purpose as that explained in connection with the previous system.

The driving motor of the motor-generafior set that is-shown in Fig. 2 comprises the armature winding M, and a stator frame or yoke SF which is provided with a plurality of oppositely-disposed, inwardly-extendmg main polar projections MP1 and MP2 and a plurality of auxiliary polar pro jections API and AP2 that are disposed in quadrature relation to the main olar 1s isposed upon the main polar projections while a shunt field winding MFl is wound around the auxiliary polar projections, as

set forth in detail later.

The circuit connections of the drivin motor under consideration may be describe as follows: The drivi -motor main circuit is completed from t e trolley through. junction-point 10, conductors 11 and 40, Junction-point 41, conductor 42, the portion of the series field winding MF that is dis posed upon the main polar projection llIPl,

conductor 43, the remaming portion of the G is connected in serieseld winding MFl that is I neti polarity, whereas the auxiliary polar projections API and AP2 oorres nd in larity to the main projections P1 and KZPQ, as designated by the characters n and a. The flux from both the main and the auxiliary north polar projections, therefore,

threads the armature winding M in the same direction.

The machine just described is well ada ted to inherently prevent flash-over con itions, by reason of the relative arrangement of mam and auxiliary polar projections with respect to the brushes 1 and 2 of the motor armature winding M. As indicatcd by the solid arrows in Fig. 2A, the main polar projection MP1 and the auxiliary polar pro]ection'AP1, which are of north magnetic polarity, create fluxes which travel from the stator frame SF through the polar projections to the armature M. The armature-reaction or cross-field flux, however, tends to op ose the flux that is emitted by the main p0 ar projection MP1, in accordance with a familiar principle; but, by reason of the peculiar location of the auxiliary polar projection API, such cros s-field flux traverses that polar pro ection in the same direction as does the auxiliary lar flux itself. The path oft-he cross-fiel flux in questionis indicated by dotted lines 1n Fig. 2 and Fig. 2A.

The location of the main and auxillary lar projections with respect to the brushes and 2 may be specifically described as follows: Assuming the direction of rotation of the armature M to be asindicated by the curved arrow in Fi 2, it will be noted that the auxiliary po ar pro ections API and AP2 are disposed near the forward or too portions of the brushes 2 and 1, respectively, whereas the mainpolar projections MP1 and MP2, being disposed intermediate the auxiliary polar pro ections, of course, are respectively located near the rear or heel portions of the brushes 2 and 1, respectively.

Assuming a sudden resumption of supplycircuit voltage after a temporary mterruption thereof, the flux that is produced by restored armature current has tended to assume abnormal roportions in most machines of the prior art and has, consequently, efi'ected an undue distortion of the simultaneous field flux, which has usually taken alonger time to build up b reason of the higher inductance of the lie d-structure magnetic circuit. Graphically, the restored armature current flux that corresponds to the initial rush of current upon the resumption of supply-circuit voltage, may be represented by t e dot-and-dash curve X of Fig. 2A whereby it will be seen that a relatively high flux value obtains adjacent to the motor commutator cylinder brush 1, for example, and, consequently, under such conditions, abnormally high volta es between commutator segments and res tant flashover conditions are liable to occur. On the other hand, the restored armature current flux within the zone of influence of the main polar pro'ection MP1, for example, in machines 0 the prior art, has assumed a relatively low value by reason of the fact that the flux that is produced by the main polar projection builds up at a comparatively rapid rate, inasmuch as the choke-coil action of the series winding is relatively small and, therefore, the armature current flux is prevented from reaching dangerous values within the zone in question.

According to my present invention, however, by reason of the above-described path of the armature-reaction or cross-field flux, the damping effect or choke-coil action of the auxiliary polar projection APl u on which the shunt-excited field windin F1 is wound, is augmented to a material degree by the combined auxiliary polar flux and cross-field flux which act cumulatively. In the main polar projection MP1, however, the rapidly increasing polar flux is partially neutralized by the effect of the cross-field flux under consideration and,consequently, the restored armature current flux attains a materially lower value than has been the case heretofore, within the zone of influence of the auxiliary polar projection API, but a somewhat higher, although not undesirable, value Wltl'lll'l the zone of influence of the main polar projection MP1, as indicated by the solid line curve Y. It will be understood that the contour of the curve Y will vary in accordance with the relative exciting fluxes of the main and the auxiliary polar projections, although, in any case, the above-described dangerously high values of restored armature current fiux are eifectively prevented.

It will be observed that I have provided a regenerative system (if control having a desirable negative com ounding characteristic whereby a substantially constant regenerated current may be maintained, and the motor-generator set that is employed for exciting the main-machine field windings, has the one or the other of its armatures provided with a com ound field winding comprising a series old-magnet winding and a shunt field-magnet winding that are connected in circuit to perform predetermined mutual functions, while the remaining armature is provided with a series-connected field winding. Both of the illustrated modifications are particularly adapted to prevent flash-over conditions in the motor-generator set, for the reasons previously pointed out.

I do not wish to be restricted to the specific circuit connections or location and arrangement of parts herein set forth, as various modifications thereof may be effected without departing from the spirit and scope of myinvention. I desire, therefore, that only such limitations shall be imposed as are indicated in the appended claims.

I claim as my invention:

1. In a system of control, the combination with a supply circuit, and a main dynamoelectric machine having an armature and a field winding, of an auxiliary motor-generator set having its armatures respectively driven from the sup ly-circuit and connected to excite said fie dwinding and havin one of said auxiliary armatures provided with differentially-related field magnet windings respectively energized from said supply-circuit and ener zed in accordance wi set.

predetermined 10 conditions of said 2. In a system of control, the combination with a supply circuit, and a main dynamoelectric machine havingan armature and a field winding, of an auxiliary motor-generator set hav' its armatures respectively driven from t e su p13 circuit and connected to excite said el winding, and havdifferentially-related field-magnet windings respectively energized from said supply circuit and energized in accordance with the driving armature load of said set and also having said drivin armature provided with a series-connected field-ma et winding.

3. In a system ofcontro the'combination with a supply circuit, and a main d nameelectric machine having an armat e and a field winding, of an auxiliary m r-generator set havin its armatures espectively driven from e s'u p1 ci it and connected to excite said e1 winding, and havsaid auxiliary armatures provided with so iiiaId windin connected in series relation with said driving armature, and means for diverting current from one of sald field windingsunder predetermined conditions.

4. In a system of control, the combination with'a supply "circuit, and a main dynamoelectric machine having an armature and a field winding, of an auxiliary motor-generator set 'eom risin -a pair of armatures res ectively driven om the supply c1rcmt co and connected to excite said fi I winding,

field-magnet windings for the respective auxilia armatures connected in series relation wit said drivin armature, andasupply-circuit-excited fie d-magnet w nding for it the exciting armature for producinga preand a field winding, of an auxiliary motoring said exciting armature provided with vtively driven from the suppl field determined voltage-fluctuation damping effect, and further damping means comprising a variable .translatm device connected in shunt to the series fie d winding of the exciting armature. v

5. In a system of direct-current regenerative control, the combination with a supply circuit, and a momentum-driven main dynamo-electric machine having an armature generator set comprising a pair of armatures respectively driven from the supply circuit and connected to excite said field winding, field-magnet windings for the respective auxilia armatures connected in series relation with said driving armatures, and a supply circuitexcited field-magnet winding for the exciting armature, and means for regulating the regenerative operat'on of the main machine, said means com rising a variable resistor connected in series relation with said supply circuitexcited field winding and a second variable resistor connected in shunt relation to the series field winding of the exciting armature.

6. In a s stem of direct-current regenerative controz the combination with a sup ly circuit, and a momentum-driven main ynamo-electric machine havin an armature and a field winding of a pair of mechanically-connected auxi iary armatures respectively driven from the supply circuit and connected to excite said field winding, means for varying the excitation of the exciting armature in accordance with the current traversing said armature, and means for varying the main field-winding current op positely to theregenerated current.

7. In a s stem of direct-current regenerative control: the combination with a supply circuit, and a momentum-driven main dynamo-electric machine havin an armature and a field winding of a pair of mechanically-cqnnected auxi iary armatures respec-' tively driven from the su dply circui and connected to excite said fiei winding, a resistor connected in series-circuit relation with said main armature and in parallelcircuit relation to said main field winding and said excitin armature, and means for 116 varying the excitation of the exciting armature in accordance with the current traversin said armature.

8. a system of direct-current regenerative control, the combination with a sup ly 12o circuit, and a momentum-driven main yname-electric machine having an armature and a field winding, of a pair of mechanisally-connected auxiliary armatures respec circuit and 126 winding, a

connected to excitesaid resistor-connected in series-circuit relation with said main annature and in parallelcircuit relation to said main field windi and said exciting armature, field-magnet 139 t6 armature, w

winding for the respective 'euxilia armetures connected in series relation iiith said d ri armature, and sufpplycircuitexcited d-magnet wind or the exciting t armature difierentially re ated with respect to the corresponding series field winding.

9. In a a stem 0 direct-currentregenerative contro the combination with a supply circuit, and a momentum-driven main name-electric machine having an armature and a field winding, ofa pair of mechanicall connected auxiliary armatures respectiv y driven from the supply circuit and connected to excite said fie winding, a resistfl' connected in series-circuit relation with said main armature and in parallelcircuit relation to said main field winding and said exciting armature, field-magnet winding for the respective auxiliary arma- 2:8 connected in series relation withsaig armatn a supp y-circuit-excite field-m et win dmg for the exciting armature di erentially related with respect to the corresponding series field winding, and means for rpgulating the regenerative operation of the main machine, said means compris' a variable resistor connected in seribs ation with said supply-circuit-excited field winding and a seecond variable resistor connected in shunt relation to the series field winding of the exciting armature.

'10. In a systcmof control, the combination with a supply1 circuit, and a main dynamo-electric mac ine having an armature and a field winding, of an auxiliary motorgenerator set having its armatures respectively driven from the supply circuit and connected to excite said field winding and having a series-related field winding for each auxiliary armature and parallel-circuit connections for regulating the efl'ect of the series field winding for said exciting armature. y

11. In a system .of control, the combination with a suppl circuit, and a main dynamo-electric mac ine having an armature and a field winding, of an auxiliary motorerator set having its armatures respectively driven from the sup ly circuit and conneetedto excite said fie -Winding, fieldmagnet windings for the respective auxilarmatures connected in series relation *wi said driving armature, and a. shuntexcited field-magpet winding for the excitcrehy said exciting armatnre isassociated with a field structure hava voltage-fluctuation damping efl'ect and t and driving armature is associated with a field structure havin a non-damping effect. G0 12., In a system 0' control, the combination with a supply circuit, and a mam d y'namo-alectric 0 having an armature and a field winding, of an auxiliary motorgen emtor set having its armptures respectively fl dri'ven from the supplym'm t m cqnuew ed to excite said field winding, a resistor and a field winding for each auxiliary armature connected in'oircuit with the motor of the motor-generator set, and means for varyin said resistor to re late theyoltage of the old winding for said exciting armature.

13. In a system of control, the combination with a supply circuit, and a main dynam0-electric mac me having an armature and '75 a field windi of a plurality of mechanisally-connects armature windin respectlvely driven from the supply circuit and connected to excite said field winding, and a plurality of difiercntially-related fieldmagnet windings for one of said armature windingsrespcctivcly energized from said supply circuit and energized in accordance with predetermined load conditions of the armature windings.

I 14. In a system of control, the combinetlon with a supply circuit, and a main dynnmo-electric machine having an armature and a field windin of a plurality of mechanicslly-connectmi armature windings respectively driven from the su ly circuit and connected to excite said field winding, a se- Tics-related field winding for each auxiliary armature windin and parallel-circuit connections for rcgu sting the effect of the series field winding for said exciting armature winding.

15. In a sysicm of control. the combination with a supply circuit, and a main dynamo-clectric machine having an armature and a Hold Winding, of a plurality of mechanically-connected armature windings respectlvcly driven from the supply circuit and connected to excite said field winding, a plurality of differentially-related field-magnet windings for said exciting armature windmg respectively energized from said supply circuit and energized in accordance with the drivin armature load, and a series-connected fiel -magnet winding for the driving armature.

16. In a System of control, the combination with a sup ly-circuit, and a main dynamo-elcctric mac me having an armature and a field winding, of an auxiliary motor-gcn- 116 orator set having its armatures respectively driven from the su ply circuit and connected to excite said fie d winding, and having a field winding for the exciting armature adapted to decrease the voltage thereof 120 upon an increase of supply-circuit voltage.

17. In a system of control, the combinatron with a supply circuit, and a main dynamo-clectrie machine having an armature and a field winding, of a plurality of mechani- 1 cally-connected armature windings respectively driven from the su ply circuit and connected -to excite said l lOld winding, a plurality of series field windings for said armature windings energized in accordance 130 with predetermined load conditions of the armature windings, and a, shunt-excited field winding for one of the armature windings.

18. In a system of control, the combination with a sup ly circuit and a, main dynamo-electric mac 'ne having an armature and. a. field winding, of an auxilia armature connected to excite said field winding, and a plurality of diiferentially-related field magnet wmdin for said'auxiliary armature respective y energized from said supply circuit and excited substantially in proortion to the load conditions of said auxiliary armature.

19. In a system of control the combination with a supgl y circuit and a main dynamo-electric mac me having an armature and a field winding, of an auxiliary armature connected to excite said field winding,a supply-circuit-e'xcited field winding for the exciting armature for producing a predetermined voltage-fiuctuation damping eflect, a

second field winding of the series type for said exciting armature, and further damping mean comprising a variable translating device connected in shunt to said series-type field winding.

20. In a system of direct-current regenerative control, the combination with a suply circuit and a momentum-driven mam ynamo-electric machine having an armature and a field winding, of an auxiliary armature connected to excite said field windi a resistor connected in series-circuit relatlon with said main armature and in arallel-circuit relation to said main field wmding and said exciting armature, and means for varying the excitation of the exciting armature substantially in proportion to the current traversing said armature.

In testimony whereof, I have hereunto subscribed my name this 29th day of April RUDOLF E. HELLMUND. 

